aceceleration problems

i changed out the motor out on my riviera and installed another series II in it, i used the original wiring harness with it and all..however, its a little sluggish from takeoff, until around 30-40 mph then it gets moving real good...my traction control/ check engine light is on as well. the other day i drove to lansing from detroit and hit 80...the car stalled and speed dropped down to around 45..on the damn freeway! so it eventually ended up picking up speed again, but it has done it a total of two times now, twice at 78 and 80 mph. my gf brother works at autozone and said since my two lights are on, its probably a bad sensor on the old harness, like an idle sensor or an egr sensor? we thought it was the fuel pump, but he said if it was that, then i wouldnt have been driving the car anyways this long

also another thing, maybe important, maybe not...where the alternator is located, there is a plug, i think its the MAP sensor or MAF sensor? its on top next to the intake, on the passenger side. when i had the old motor taken out, the plug wasnt connected and the guy said since it wasnt originally hooked up, i didnt need it. there also isnt a plug on my harness that fits into that sensor either...could that affect the problem above? does anyone else have this plug thats unplugged? id hate to go all through it with some mechanics when it was jsut a missing plug that i can get off any harness, since i see its on a grand prix harness with the same motor...

Can you put some extra information about your car in your signature please? What year at least would be helpful.

Thanks

Sounds like your MAF may not be working right to be sluggish like that, but you should be getting a SES light for that.

thanks with the signature

the guy said i didnt need that plug but i was wondering..why would gm put a damn plug on a motor if it wasnt needed? im no mechanic or car buff but damn...lol

There are occasionally 'extra' plugs from the factory, i.e. something in the wiring harness that is not on all vehicles, or you have a '96 harness in a '95 car, stuff like that.

Did I read that you put a S/C Series II engine in a '95 that had a N/A Series II?

deekster_caddy wrote:

There are occasionally 'extra' plugs from the factory, i.e. something in the wiring harness that is not on all vehicles, or you have a '96 harness in a '95 car, stuff like that.

Did I read that you put a S/C Series II engine in a '95 that had a N/A Series II?

nah its a NA Series II, but its from a 1997 Century I think, but the harness is from the original motor/car. But the harness from the original motor didnt have that plug on it though